Low resistivity films containing molybdenum

ABSTRACT

Provided herein are low resistance metallization stack structures for logic and memory applications and related methods of fabrication. In some implementations, the methods involve providing a tungsten (W)-containing layer on a substrate; and depositing a molybdenum (Mo)-containing layer on the W-containing layer. In some implementations, the methods involve depositing a Mo-containing layer directly on a dielectric or titanium nitride (TiN) substrate without an intervening W-containing layer.

INCORPORATION BY REFERENCE

An Application Data Sheet is filed concurrently with this specificationas part of the present application. Each application that the presentapplication claims benefit of or priority to as identified in theconcurrently filed Application Data Sheet is incorporated by referenceherein in its entirety and for all purposes.

BACKGROUND

The background description provided herein is for the purposes ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentdisclosure.

Tungsten (W) film deposition using chemical vapor deposition (CVD)techniques is an integral part of semiconductor fabrication processes.For example, tungsten films may be used as low resistivity electricalconnections in the form of horizontal interconnects, vias betweenadjacent metal layers, and contacts between a first metal layer and thedevices on a silicon substrate. Tungsten films may also be used invarious memory applications, including in formation of buried wordline(bWL) architectures for dynamic random access memory (DRAM), and logicapplications. In an example of bWL deposition, a tungsten layer may bedeposited on a titanium nitride (TiN) barrier layer to form a TiN/Wbilayer by a CVD process using WF₆. However, the continued decrease infeature size and film thickness bring various challenges to TiN/W filmstacks. These include high resistivity for thinner films anddeterioration of TiN barrier properties.

SUMMARY

One aspect of the disclosure relates to methods including providing atungsten (W)-containing layer on a substrate; and depositing amolybdenum (Mo)-containing layer on the W-containing layer. In someembodiments, the W-containing layer is a WCN layer. In some embodiments,the W-containing layer is a W nucleation layer. In some embodiments, theW-containing layer is deposited from one or more tungsten chlorideprecursors. In some embodiments, the Mo-containing layer is a Mo layerhaving less than 1 (atomic) % impurities. In some embodiments, themethod includes thermally annealing the Mo-containing layer. In someembodiments, the Mo-containing layer is deposited by exposing theW-containing layer to a reducing agent and a Mo-containing precursorselected from: molybdenum hexafluoride (MoF₆), molybdenum pentachloride(MoCl₅), molybdenum dichloride dioxide (MoO₂Cl₂), molybdenumtetrachloride oxide (MoOCl₄), and molybdenum hexacarbonyl (Mo(CO)₆). Insome embodiments, a substrate temperature during exposure to theMo-containing precursor is less than 550° C. In some embodiments, thesubstrate is exposed to the reducing agent at first substratetemperature and is exposed to the Mo-containing precursor at a secondsubstrate temperature, wherein the first substrate temperature is lessthan the second substrate temperature. In some embodiments, the reducingagent is a mixture of a boron-containing reducing agent and asilicon-containing reducing agent.

Another aspect of the disclosure relates to method including flowing areducing agent gas to a process chamber housing a substrate, at a firstsubstrate temperature to form a conformal reducing agent layer on thesubstrate; and exposing the conformal reducing agent layer to amolybdenum (Mo)-containing precursor at a second substrate temperatureto convert the reducing agent layer to molybdenum. In some embodiments,the first substrate temperature is less than the second substratetemperature. In some embodiments, the reducing agent is a mixture of aboron-containing reducing agent and a silicon-containing reducing agent.In some embodiments, the first substrate temperature is no more than400° C. and the second substrate temperature is at least 500° C. In someembodiments, the methods further include annealing the molybdenum.

Another aspect of the disclosure relates to a method including pulsing areducing agent, wherein the reducing agent is boron (B)-containing,silicon (Si)-containing or germanium (Ge)-containing; and pulsing aMo-containing precursor, wherein the Mo-containing precursor is reducedby the reducing agent or a product thereof to form a multi-componenttungsten-containing film containing one or more of B, Si, and Ge on thesubstrate. In some embodiments, the multi-component tungsten-containingfilm contains between 5% and 60% (atomic) B, Si, or Ge. In someembodiments, the between 5% and 60% (atomic) B, Si, or Ge is provided bythe reducing agent.

Another aspect of the disclosure are apparatuses for performing themethods disclosed herein. These and other features are discussed furtherwith respect to the drawings.

BRIEF DESCRIPTIONS OF DRAWINGS

FIGS. 1A and 1B are schematic examples of material stacks that includemolybdenum (Mo) according to various embodiments.

FIG. 2 depicts a schematic example of a DRAM architecture including a Moburied wordline (bWL).

FIG. 3A depicts a schematic example of a Mo wordline in a 3D NANDstructure.

FIG. 3B depicts a 2-D rendering of 3-D features of apartially-fabricated 3D NAND structure after Mo fill including a Mowordline and a conformal barrier layer.

FIGS. 4A and 4B provide process flow diagrams for methods performed inaccordance with disclosed embodiments.

FIGS. 5 and 6 are graphs showing Mo thickness (Angstroms) vs. CVDDuration (seconds) and Mo Resistivity (μΩ-cm) vs Mo thickness(Angstroms), respectively, for various substrate temperatures andchamber pressures for CVD deposition of Mo on tungsten (W) nucleationlayers.

FIGS. 7 and 8 are graphs showing Mo growth rate and resistivity vs Mofilm thickness, respectively, for CVD deposition of Mo on WCN at varioussubstrate temperatures and chamber pressures.

FIG. 9 is a graph showing thickness and resistivity of a CVD depositedMo layer as a function of WCN underlayer thickness.

FIG. 10 is a graph showing the reduction in stack resistivity for Mostacks of various thicknesses deposited on 2 nm WCN after anneal at 800°C.

FIG. 11 is a block diagram of a processing system suitable forconducting deposition processes in accordance with embodiments describedherein.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth toprovide a thorough understanding of the presented embodiments. Thedisclosed embodiments may be practiced without some or all of thesespecific details. In other instances, well-known process operations havenot been described in detail to not unnecessarily obscure the disclosedembodiments. While the disclosed embodiments will be described inconjunction with the specific embodiments, it will be understood that itis not intended to limit the disclosed embodiments.

Provided herein are low resistance metallization stack structures forlogic and memory applications. FIGS. 1A and 1B are schematic examples ofmaterial stacks that include molybdenum (Mo) according to variousembodiments. FIGS. 1A and 1B illustrate the order of materials in aparticular stack and may be used with any appropriate architecture andapplication, as described further below with respect to FIGS. 2 and 3.In the example of FIG. 1A, a substrate 102 has a Mo layer 108 isdeposited thereon. The substrate 102 may be a silicon or othersemiconductor wafer, e.g., a 200-mm wafer, a 300-mm wafer, or a 450-mmwafer, including wafers having one or more layers of material, such asdielectric, conducting, or semi-conducting material deposited thereon.The methods may also be applied to form metallization stack structureson other substrates, such as glass, plastic, and the like.

In FIG. 1A, a dielectric layer 104 is on the substrate 102. Thedielectric layer 104 may be deposited directly on a semiconductor (e.g.,Si) surface of the substrate 102, or there may be any number ofintervening layers. Examples of dielectric layers include doped andundoped silicon oxide, silicon nitride, and aluminum oxide layers, withspecific examples including doped or undoped layers SiO₂ and Al₂O₃.Also, in FIG. 1A, a diffusion barrier layer 106 is disposed between theMo layer 108 and the dielectric layer 104. Examples of diffusion barrierlayers including titanium nitride (TiN), titanium/titanium nitride(Ti/TiN), tungsten nitride (WN), and tungsten carbon nitride (WCN).Further examples diffusion barriers are multi-component Mo-containingfilms as described further below. The Mo layer 108 is the main conductorof the structure. As discussed further below, the Mo layer 108 mayinclude a Mo nucleation layer and a bulk Mo layer. Further, in someembodiments, the Mo layer 108 may be deposited on a tungsten (W) orW-containing growth initiation layer.

FIG. 1B shows another example of a material stack. In this example, thestack includes the substrate 102, dielectric layer 104, with Mo layer108 deposited on the dielectric layer 104, without an interveningdiffusion barrier layer. As in the example of FIG. 1A, the Mo layer 108may include a Mo nucleation layer and a bulk Mo layer, and, in someembodiments, the Mo layer 108 may be deposited on a tungsten (W) orW-containing growth initiation layer. By using Mo, which has a lowerelectron mean free path than W, as the main conductor, lower resistivitythin films can be obtained.

While FIGS. 1A and 1B show examples of metallization stacks, the methodsand resulting stacks are not so limited. For example, in someembodiments, Mo may be deposited directly on a Si or other semiconductorsubstrate, with or without a W initiation layer.

The material stacks described above and further below may be employed ina variety of embodiments. FIGS. 2, 3A, and 3B provide examples ofstructures in which the Mo-containing stacks may be employed. FIG. 2depicts a schematic example of a DRAM architecture including a Mo buriedwordline (bWL) 208 in a silicon substrate 202. The Mo bWL is formed in atrench etched in the silicon substrate 202. Lining the trench is aconformal barrier layer 206 and an insulating layer 204 that is disposedbetween the conformal barrier layer 206 and the silicon substrate 202.In the example of FIG. 2, the insulating layer 204 may be a gate oxidelayer, formed from a high-k dielectric material such as a silicon oxideor silicon nitride material. In some embodiments disclosed herein theconformal barrier layer is TiN or tungsten-containing layer. In someembodiments, it TiN is used as a barrier, a conformaltungsten-containing growth initiation layer may be present between theconformal barrier layer 206 and the Mo bWL 208. Alternatively, the MobWL 208 may be deposited directly on a TiN or other diffusion barrier.

FIG. 3A depicts a schematic example of a Mo wordline 308 in a 3D NANDstructure 323. In FIG. 3B, a 2-D rendering of 3-D features of apartially-fabricated 3D NAND structure after Mo fill, is shown includingthe wordline 308 and a conformal barrier layer 306. FIG. 3B is across-sectional depiction of a filled area with the pillar constrictions324 shown in the figure representing constrictions that would be seen ina plan rather than cross-sectional view. The conformal barrier layer 306may be a TiN or tungsten-containing layer as described above withrespect to the conformal barrier layer 206 in FIG. 2. In someembodiments, a tungsten-containing film may serve as a barrier layer anda nucleation layer for subsequent CVD Mo deposition as discussed below.If TiN is used as a barrier, a conformal tungsten-containing growthinitiation layer may be present between the barrier and the wordline.Alternatively, the Mo wordline 308 may be deposited directly on a TiN orother diffusion barrier.

The methods of forming Mo-containing stacks include vapor depositiontechniques such as CVD and pulsed nucleation layer (PNL) deposition. Ina PNL technique, pulses of a co-reactant, optional purge gases, andMo-containing precursor are sequentially injected into and purged fromthe reaction chamber. The process is repeated in a cyclical fashionuntil the desired thickness is achieved. PNL broadly embodies anycyclical process of sequentially adding reactants for reaction on asemiconductor substrate, including atomic layer deposition (ALD)techniques. PNL may be used for deposition of Mo nucleation layersand/or W-based growth initiation layers in the methods described herein.A nucleation layer is typically a thin conformal layer that facilitatessubsequent deposition of bulk material thereon. According to variousimplementations, a nucleation layer may be deposited prior to any fillof the feature and/or at subsequent points during fill of the feature.

PNL techniques for depositing tungsten nucleation layers are describedin U.S. Pat. Nos. 6,635,965; 7,005,372; 7,141,494; 7,589,017, 7,772,114,7,955,972 and 8,058,170. Nucleation layer thickness can depend on thenucleation layer deposition method as well as the desired quality ofbulk deposition. In general, nucleation layer thickness is sufficient tosupport high quality, uniform bulk deposition. Examples may range from10 Å-100 Å.

In many implementations, deposition of the Mo bulk layer can occur by aCVD process in which a reducing agent and a Mo-containing precursor areflowed into a deposition chamber to deposit a bulk layer in the feature.An inert carrier gas may be used to deliver one or more of the reactantstreams, which may or may not be pre-mixed. Unlike PNL or ALD processes,this operation generally involves flowing the reactants continuouslyuntil the desired amount is deposited. In certain implementations, theCVD operation may take place in multiple stages, with multiple periodsof continuous and simultaneous flow of reactants separated by periods ofone or more reactant flows diverted.

Mo-containing precursors include molybdenum hexafluoride (MoF₆),molybdenum pentachloride (MoCl₅), molybdenum dichloride dioxide(MoO₂Cl₂), molybdenum tetrachloride oxide (MoOCl₄), and molybdenumhexacarbonyl (Mo(CO)₆). Organometallic precurors such as molybdenumsilylcyclopentadienyl and molybdenum silylallyl complexes may be used.Mo-containing precursors may be halide precursors, which include MoF₆and MoCl₅ as well as mixed halide precursors that have two or morehalogens that can form a stable molecule. An example of a mixed halideprecursor is MoCl_(x)Br_(y) with x and y being any number greater than 0that can form a stable molecule.

Mo-Containing Layer on a W-Based Growth Initiation Layer

In certain embodiments, structures including a molybdenum(Mo)-containing layer on a tungsten (W)-based growth initiation layerare provided. Also provided are methods of forming Mo-containing films.

The W-based growth initiation layer may be any W-containing layer. Insome embodiments, it is a nucleation layer, i.e., a thin conformal layerthat serves to facilitate the subsequent formation of a bulk materialthereon. In some embodiments, the W-based growth initiation layer is abulk W-containing layer, which itself may be deposited on a nucleationlayer. When used for feature fill, a nucleation layer may be depositedto conformally coat the sidewalls and bottom of the feature. Conformingto the underlying feature bottom and sidewalls can be critical tosupport high quality deposition. According to various embodiments, theW-based growth initiation layer may be deposited by one or both of PNLand CVD. For example, a CVD layer may be deposited on a PNL layer.

In some embodiments, the W-containing layer is an elemental W layer.Such layers may be deposited by any appropriate methods include PNL orCVD methods. Elemental W is distinguished from binary films such as WCor WN and ternary films like WCN, though it may include some amount ofimpurities. It may be referred to as a W layer or W film.

In some embodiments, the W-based growth layer is a low resistivity W(LRW) film. Deposition of low resistivity tungsten according to certainembodiments is described in U.S. Pat. No. 7,772,114. In particular, the'114 patent describes exposing a PNL W nucleation layer to a reducingagent prior to CVD deposition of W on the PNL W layer. LRW films havelarge grain sizes that provide good templates for large Mo grain growth.

In some embodiments, the W-based growth layer is a PNL W nucleationlayer deposited using one or more of a boron-containing reducing agent(e.g., B₂H₆) or a silicon-containing reducing agent (e.g., SiH₄) as aco-reactant. For example, one or more S/W cycles, where S/W refers to apulse of silane followed by a pulse of tungsten hexafluoride (WF₆) orother tungsten-containing precursor, may be employed to deposit a PNL Wnucleation layer on which a Mo layer is deposited. In another example,one or more B/W cycles, where B/W refers to a pulse of diborane followedby a pulse of WF₆ or other tungsten-containing precursor, may beemployed to deposit a PNL W nucleation layer on which a Mo layer isdeposited. B/W and S/W cycles may both be used to deposit a PNL Wnucleation layer. Examples of PNL processes using one or both of aboron-containing reducing agent and a silicon-containing reducing agentare described in U.S. Pat. Nos. 7,262,125; 7,589,017; 7,772,114;7,955,972; 8,058,170; 9,236,297 and 9,583,385.

In some embodiments, the W-based growth layer is a W layer or otherW-containing layer deposited using a tungsten chloride (WCl_(x))precursor such as tungsten hexachloride (WCl₆) or tungsten pentachloride(WCl₅). Deposition of W-containing layers using tungsten chlorides isdescribed in U.S. Pat. No. 9,595,470; U.S. Patent Publication No.20150348840; and U.S. patent application Ser. No. 15/398,462.

In some embodiments, the W-based growth layer is a low fluorine W layer.U.S. Pat. No. 9,613,818, describes sequential CVD methods of depositinga low-fluorine W layer. U.S. Patent Publication No. 2016/0351444describes PNL methods of depositing low fluorine W layers.

In some embodiments, the W-based growth layer is a WN, WC, or WCN film.Methods of depositing one or more of WN, WC, or WCN are described ineach of U.S. Pat. Nos. 7,005,372; 8,053,365; 8,278,216; and U.S. patentapplication Ser. No. 15/474,383.

The W-based growth layers are not limited to the examples given above,but may be any W or other W-containing film deposited by any appropriatemethod including ALD, PNL, CVD, or physical vapor deposition (PVD)methods. ALD, PNL, and CVD deposition involves exposure to aW-containing precursor. In addition to the WF₆ and WCl_(x) precursors,examples of W-containing precursors include tungsten hexacarbonyl(W(CO)₆) and organo-metallic precursors such as MDNOW (methylcyclopentadienyl-dicarbonylnitrosyl-tungsten) and EDNOW(ethylcyclopentadienyl-dicarbonylnitrosyl-tungsten). In many ALD, PNL,and CVD deposition processes, a reducing agent is used to reduce theW-containing precursor. Examples include hydrogen gas (H₂), silane(SiH₄), disilane (Si₂H₆) hydrazine (N₂H₄), diborane (B₂H₆) and germane(GeH₄).

Also as noted above, the W-containing films described herein may includesome amount of other compounds, dopants and/or impurities such asnitrogen, carbon, oxygen, boron, phosphorous, sulfur, silicon, germaniumand the like, depending on the particular precursors and processes used.The tungsten content in the film may range from 20% to 100% (atomic)tungsten. In many implementations, the films are tungsten-rich, havingat least 50% (atomic) tungsten, or even at least about 60%, 75%, 90%, or99% (atomic) tungsten. In some implementations, the films may be amixture of elemental tungsten (W) and other tungsten-containingcompounds such as WC, WN, etc.

The Mo-containing film may be deposited on the W-based growth initiationlayer by any appropriate method including ALD or CVD. In someembodiments, sequential CVD processes may be used. Sequential CVDprocesses are described in U.S. Pat. No. 9,613,818, incorporated byreference herein.

Deposition of Mo-containing films may involve exposing the W-basedgrowth initiation layer to a Mo-containing precursor and a reducingagent or other co-reactant, either simultaneously or sequentially.Examples of Mo-containing precursors include MoF₆, MoCl₅, MoOCl₄, andMo(CO)₆. Organometallic precurors such as molybdenumsilylcyclopentadienyl and molybdenum silylallyl complexes may be used.Mo film purity (e.g., as measured by O content) can be tuned by varyingthe precursor and co-reactant partial pressures.

Substrate temperature during Mo deposition may be between 300° C. to750° C., and in particular embodiments, between 450° C. and 550° C.Substrate temperature will depend on the thermal budget and thedeposition chemistry. Thermal budget depends on the applications, whilehigh deposition temperature may not be an issue for memory applications,it can exceed the thermal budget for logic applications.

The presence of the W-containing growth initiation layer allows thedeposition to be performed at lower temperatures. For example, Modeposition from MoCl₅ or MoOCl₄ cannot be performed at temperatures lessthan 550° C. due to the strength of the Mo—Cl bond. However, with aW-containing growth initiation layer, the deposition can be performed atless than 550° C. Chamber pressure during Mo deposition may be, forexample, 5 torr to 60 torr.

In some embodiments, H₂ is used as reducing agent, rather than astronger reducing agent such SiH₄ or B₂H₆. These stronger reducingagents can result in an undesirable oxygen rich interface when using anoxygen-containing Mo-containing precursor. The Mo-containing film may anelemental Mo film, although such films may include some amount of othercompounds, dopants and/or impurities depending on the particularprecursors and processes used.

Mo-Containing Layer on a PNL-Deposited Mo Nucleation Layer

In certain embodiments, a Mo-containing layer may be deposited withoutthe use of a W-based growth initiation layer. For example, an elementalMo layer may be deposited on a TiN or dielectric layer. For certainprecursors, deposition temperatures may be relatively high (above 550°C.) to obtain deposition. CVD deposition using chlorine-containingprecursors such as MoOCl₅, MoOCl₄, and MoO₂Cl₂ may be performed attemperatures of greater than 550° C. on TiN and dielectric surfaces. Atlower temperatures, CVD deposition may be performed on any surface usinga W-based growth initiation layer as described above. Further, in someembodiments, CVD deposition may be performed on any surface using aMo-containing nucleation layer deposited by a PNL process.

As described above, in a PNL process, pulses of a co-reactant, optionalpurge gases, and Mo-containing precursor are sequentially injected intoand purged from the reaction chamber. In some embodiments, a Monucleation layer deposited using one or more of a boron-containingreducing agent (e.g., B₂H₆) or a silicon-containing reducing agent(e.g., SiH₄) as a co-reactant. For example, one or more S/Mo cycles,where S/Mo refers to a pulse of silane followed by a pulse of aMo-containing precursor, may be employed to deposit a PNL Mo nucleationlayer on which a CVD Mo layer is deposited. In another example, one ormore B/Mo cycles, where B/Mo refers to a pulse of diborane followed by apulse of a Mo-containing precursor, may be employed to deposit a PNL Monucleation layer on which a CVD Mo layer is deposited. B/Mo and S/Mocycles may both be used to deposit a PNL Mo nucleation layer, e.g.,x(B/Mo)+y(S/Mo), with x and y being integers. For PNL deposition of a Monucleation layers, in some embodiments, the Mo-containing precursor maybe a non-oxygen containing precursor, e.g., MoF₆ or MoCl₅. Oxygen inoxygen-containing precursors may react with a silicon- orboron-containing reducing agent to form MoSi_(x)O_(y) or MoB_(x)O_(y),which are impure, high resistivity films. Oxygen-containing precursorsmay be used with oxygen incorporation minimized. In some embodiments, H₂may be used as a reducing gas instead of a boron-containing orsilicon-containing reducing gas. Example thicknesses for deposition of aMo nucleation layer range from 5 Å to 30 Å. Films at the lower end ofthis range may not be continuous; however, as long as they can helpinitiate continuous bulk Mo growth, the thickness may be sufficient. Insome embodiments, the reducing agent pulses may be done at lowersubstrate temperatures than the Mo precursor pulses. For example, orB₂H₆ or a SiH₄ (or other boron- or silicon-containing reducing agent)pulse may be performed at a temperature below 300° C., with the Mo pulseat temperatures greater than 300° C.

Mo Deposition Using a Reducing Agent Layer

Deposition at lower temperatures (below 550° C.) may also be performeddirectly on non-W surfaces such as dielectric and TiN surfaces by aprocess as shown in FIG. 4A. It may also be used on W-containingsurfaces. FIG. 4A provides a process flow diagram for a method performedin accordance with disclosed embodiments. Operations 402-408 of FIG. 4Amay be performed to form a conformal Mo layer directly at least adielectric surface or other surface.

In operation 402, the substrate is exposed to a reducing agent gas toform a reducing agent layer. In some embodiments, the reducing agent gasmay be a silane, a borane, or a mixture of a silane and diborane.Examples of silanes including SiH₄ and Si₂H₆ and examples of boranesinclude diborane (B₂H₆), as well as B_(n)H_(n+4), B_(n)H_(n+6),B_(n)H_(n+8), B_(n)H_(m), where n is an integer from 1 to 10, and m is adifferent integer than m. Other boron-containing compounds may also beused, e.g., alkyl boranes, alkyl boron, aminoboranes (CH₃)₂NB(CH₂)₂,carboranes such as C₂B_(n)H_(n+2). In some implementations, the reducingagent layer may include silicon or silicon-containing material,phosphorous or a phosphorous-containing material, germanium or agermanium-containing material, boron or boron-containing material thatis capable of reducing a tungsten precursor and combinations thereof.Further example reducing agent gases that can be used to form suchlayers include PH₃, SiH₂Cl₂, and GeH₄. According to various embodiments,hydrogen may or may not be run in the background. (While hydrogen canreduce tungsten precursors, it does not function as a reducing agent ina gas mixture with a sufficient amount of stronger reducing agents suchas silane and diborane.)

In some embodiments, the reducing agent gas is a mixture including asmall amount of a boron-containing gas, such as diborane, with anotherreducing agent. The addition of a small amount of a boron-containing gascan greatly affect the decomposition and sticking coefficient of theother reducing agent. It should be noted that exposing the substratesequentially to two reducing agents, e.g., silane and diborane may beperformed. However, flowing a mixture of gases can facilitate theaddition of very small amounts of a minority gas, e.g., at least a 100:1ratio of silane to diborane. In some embodiments, a carrier gas may beflowed. In some embodiments, a carrier gas, such as nitrogen (N₂), argon(Ar), helium (He), or other inert gases, may be flowed during operation402.

In some embodiments, a reducing agent layer may include elementalsilicon (Si), elemental boron (B), elemental germanium (Ge), or mixturesthereof. For example, as described below, a reducing agent layer mayinclude Si and B. The amount of B may be tailored to achieve highdeposition rate of the reducing agent layer but with low resistivity. Insome embodiments, a reducing agent layer may have between 5% and 80% Bfor example, or between 5% and 50% B, between 5% and 30%, or between 5%and 20% B, with the balance consisting essentially of Si and in somecases, H. Hydrogen atoms be present, e.g., SiH_(x), BH_(y), GeH_(z), ormixtures thereof where x, y, and z may independently be between 0 and anumber that is less than the stoichiometric equivalent of thecorresponding reducing agent compound.

In some embodiments, the composition may be varied through the thicknessof the reducing agent layer. For example, a reducing agent layer may be20% B at the bottom of the reducing agent layer and 0% B the top of thelayer. The total thickness of the reducing agent layer may be between 10Å and 50 Å, and is some embodiments, between 15 Å and 40 Å, or 20 Å and30 Å. The reducing agent layer conformally lines the feature.

Substrate temperature during operation 402 may be maintained at atemperature T1 for the film to be conformal. If temperature is too high,the film may not conform to the topography of the underlying structure.In some embodiments, step coverage of greater than 90% or 95% isachieved. For silane, diborane, and silane/diborane mixtures,conformality is excellent at 300° C. and may be degraded at temperaturesof 400° C. or higher. Thus, in some embodiments, temperature duringoperation 202 is at most 350° C., or even at most 325° C., at most 315°C., or at most 300° C. In some embodiments, temperatures of less than300° C. are used. For example, temperatures may be as low as 200° C.

Operation 402 may be performed for any suitable duration. In someexamples, Example durations include between about 0.25 seconds and about30 seconds, about 0.25 seconds and about 20 seconds, about 0.25 secondsand about 5 seconds, or about 0.5 seconds and about 3 seconds.

In operation 404, the chamber is optionally purged to remove excessreducing agent that did not adsorb to the surface of the substrate. Apurge may be conducted by flowing an inert gas at a fixed pressurethereby reducing the pressure of the chamber and re-pressurizing thechamber before initiating another gas exposure. Example inert gasesinclude nitrogen (N₂), argon (Ar), helium (He), and mixtures thereof.The purge may be performed for a duration between about 0.25 seconds andabout 30 seconds, about 0.25 seconds and about 20 seconds, about 0.25seconds and about 5 seconds, or about 0.5 seconds and about 3 seconds.

In operation 406, the substrate is exposed to a Mo-containing precursorat a substrate temperature T2. Examples of Mo-containing compounds aregiven above and include chlorides and oxychlorides. Use ofoxygen-containing precursors can lead to impurity incorporation andhigher resistivity. However, if oxygen is incorporated, a very thin,possibly discontinuous reducing agent layer may be used for anacceptable resistivity. In some embodiments, a carrier gas, such asnitrogen (N₂), argon (Ar), helium (He), or other inert gases, may beflowed during operation 406. Examples of temperatures are 500° C. to700° C.

Operation 406 may be performed for any suitable duration. In someembodiments, it may involve a soak of the Mo-containing precursor and insome embodiments, a sequence of Mo-containing precursor pulses.According to various embodiments, operation 406 may or may not beperformed in the presence of H₂. If H₂ is used, in some embodiments, itand the Mo-containing precursor may be applied in an ALD-type mode. Forexample:

Pulse of H₂

Argon purge

Pulse of Mo-containing precursor with or without H₂ in background

Argon purge

Repeat

The substrate temperature T2 is high enough that the Mo-containingprecursor reacts with the reducing agent layer to form elemental Mo. Theentire reducing agent layer is converted to Mo. In some embodiments, thetemperature is at least 450° C., and may be at least 550° C. to obtainconversion of at or near 100%. The resulting feature is now lined with aconformal film of Mo. It may be between 10 Å and 50 Å, and is someembodiments, between 15 Å and 40 Å, or 20 Å and 30 Å. In general, itwill be about the same thickness as the reducing agent layer. In someembodiments, it may be may be up to 5% thicker than the reducing agentlayer due to volumetric expansion during the conversion. In someembodiments, a CVD Mo layer may be deposited on the conformal Mo layer.

Multi-Component Mo Film

In some embodiments, a multi-component Mo-containing film is provided.In some such embodiments, the multi-component Mo-containing film mayinclude one or more of boron (B), silicon (Si), or germanium (Ge). FIG.4B provides a process flow diagram for a method performed in accordancewith disclosed embodiments.

First, a substrate is exposed to a reducing agent pulse (452). In someembodiments, a surface that is exposed to the reducing agent pulse onwhich the film is formed is a dielectric. According to variousembodiments, the film may be formed on other types of surfaces includingconducting and semiconducting surfaces.

The reducing agent employed in block 452 will reduce a Mo-containingprecursor employed in a subsequent operation as well as provide acompound to be incorporated into the resulting film. Examples of suchreducing agents include boron-containing, silicon-containing, andgermanium-containing reducing agents. Examples of boron-containingreducing agents include boranes such B_(n)H_(n+4), B_(n)H_(n+6),B_(n)H_(n+8), B_(n)H_(m), where n is an integer from 1 to 10, and m is adifferent integer than m. In particular examples, diborane may beemployed. Other boron-containing compounds may also be used, e.g., alkylboranes, alkyl boron, aminoboranes (CH₃)₂NB(CH₂)₂, and carboranes suchas C₂B_(n)H_(n+2). Examples of silicon-containing compounds includesilanes such as SiH₄ and Si₂H₆. Examples of germanium-containingcompounds include germanes, such as Ge_(n)H_(n+4), Ge_(n)H_(n+6),Ge_(n)H_(n+8), and Ge_(n)H_(m), where n is an integer from 1 to 10, andn is a different integer than m. Other germanium-containing compoundsmay also be used, e.g., alkyl germanes, alkyl germanium, aminogermanesand carbogermanes.

According to various embodiments, block 452 may involve adsorption of athin layer of thermally decomposed elemental boron, silicon, orgermanium onto the surface of the substrate. In some embodiments, block452 may involve adsorption of a precursor molecule onto substratesurface.

Next, the chamber in which the substrate sits may be optionally purged(454). A purge pulse or an evacuation can be employed to remove anybyproduct, if present, and unadsorbed precursor. This is followed by apulse of a Mo-containing precursor (456). In some embodiments, theMo-containing precursor is a Cl-containing precursor such as MoOCl₄,MoO₂Cl₂, and MoCl₅. An optional purge (457) may be performed after block456 as well. The Mo-containing precursor is reduced by the reducingagent (or a decomposition or reaction product thereof) to form themulti-component film.

A deposition cycle will typically deposit a portion of the Mo-containinglayer. After block 457, a deposition cycle may be complete in someimplementations with the deposited film being a tungsten-containingbinary film such as MoB_(x), MoSi_(x), and MoGe_(x), where x is greaterthan zero. In such embodiments, the process may proceed to block 462with repeating the cycle of blocks 452-457 until the desired thicknessis deposited. Example growth rates may be about 100 Å per cycle.

In some embodiments, the process will proceed with optionallyintroducing a third reactant (458). The third reactant will generallycontain an element to be introduced into the film, such as carbon ornitrogen. Examples of nitrogen-containing reactants include N₂, NH₃, andN₂H₄. Examples of carbon-containing reactants include CH₄ and C₂H₂. Anoptional purge (459) may follow. The process may then proceed to block462 with repeating the deposition cycle.

Examples of ternary films including nitrogen or carbon are given above.In some embodiments, a film may include both nitrogen and carbon (e.g.,MoSiCN).

According to various embodiments, the multi-component tungsten film mayhave the following atomic percentages: Mo about 5% to 90%, B/Ge/Si about5% to 60%, C/N about 5% to 80%. In some embodiments, the multi-componentfilms have the following atomic percentages: Mo about 15% to about 80%;B/Ge/Si: about 15% to about 50%; and C/N about 20% to about 50%.According to various embodiments, the multi-component Mo film is atleast 50% Mo.

According to various embodiments, the deposition is relatively high,e.g., between 500° C. and 700° C., including between 550° C. and 650°C., and in some embodiments greater than about 500° C. This facilitatesMo-containing precursor reduction and also permits incorporation of B,Si, or Ge into the binary film. The high end of the range may be limitedby thermal budget considerations. In some embodiments, any one or moreof blocks 452, 456, and 458 may be performed at a different temperaturethan any of the other blocks. In certain embodiments, transitioning fromblock 452 to block 456 and from block 456 to block 458 involves movingthe substrate from one deposition station to another in a multi-stationchamber. Still further, each of block 452, block 456, and block 458 maybe performed in a different station of the same multi-station chamber.In some embodiments, the order of blocks 452, 456, and 458 may bechanged.

In some embodiments, electrical properties such as work function of thebinary or ternary film may be tuned by introducing nitrogen or carbon.Similarly, the amount of reducing agent may be modulated (by modulatingdosage amount and/or pulse time) to tune the amount of B, Si, or Ge thatis incorporated into the film. Still further, any one or two of blocks452, 456 and 458 may be performed more than once per cycle to tune therelative amounts of the tungsten and the other components of the binaryor ternary films and thus their physical, electrical, and chemicalcharacteristics. The multi-component layer may include Mo, one or moreof B, Si, and Ge, and, optionally, one or more of C and N. Examplesinclude MoB_(x), MoSi_(x), MoGe_(x), MoB_(x)N_(y), MoSi_(x)N_(y),MoGe_(x)N_(y), MoSi_(x)C_(y), MoB_(x)C_(y), MoGe_(x)C_(y), where x and yare greater than zero.

It should be noted that in the process described with reference to FIG.4B, an element in the reducing agent (B, Si, or Ge) is deliberatelyincorporated into the Mo-containing film. This is in contrast to certainPNL and CVD deposition processes described above and certain embodimentsof the deposition process described in FIG. 4B in which a B-containing,Si-containing, or Ge-containing reducing agent may be used to form anelement Mo film that has none of or only trace amounts of theseelements. Incorporation of B, Ge, or Si can be controlled by the pulseduration and dosage amount. Further, in some embodiments, highertemperatures may be employed to increase incorporation. If thetemperature is too high, it can result in uncontrolled decomposition ofthe reactant gas. In some embodiments, the substrate temperature may belower temperature for the reducing agent gas and a higher temperaturefor the Mo precursor, as described above with respect to FIG. 4A.

In some embodiments, the process in FIG. 4B may be modified such that B,Si, or Ge is not incorporated into the film, but block 458 is performedto incorporate C and/N, e.g., to form MoC, MoN, or MoCN films. A C-and/or N-containing reactant may be used in such embodiments.

In some embodiments, the multi-component Mo-containing film is adiffusion barrier, e.g., for a wordline. In some embodiments, themulti-component tungsten-containing film is a work function layer for ametal gate. In some embodiments, a bulk Mo layer may deposited on themulti-component layer. The bulk layer may be deposited directly on themulti-component Mo-containing film without an intervening layer in someembodiments. In some embodiments, it may be deposited by CVD.

Experimental

CVD Mo films were grown on tungsten nucleation layers deposited by PNLusing silane and diborane, respectively, to reduce WF₆. Thesilane-deposited tungsten nucleation layer is referred to as a SWnucleation layer, and the diborane-deposited tungsten nucleation layeris referred to as a BW nucleation layer. Mo films were deposited fromMoOCl₄ and H₂.

30 Torr and 45 Torr process pressures were compared for each deposition.No Mo deposition and some W loss was observed at 30 Torr, with more Wloss observed for BW nucleation than SW nucleation. Secondary ion massspectrometry (SIMS) data showed O content at less than 1 atomic %.

Mo was deposited by CVD on SW nucleation layers and BW nucleation layersat different temperatures (500° C. and 520° C.), pressures (45 Torr and60 Torr). The number of BW or SW cycles use to deposit the nucleationlayer was also varied (1, 2, 3 or 4). FIGS. 5 and 6 show Mo thickness(Angstroms) vs. CVD Duration (seconds) and Mo Resistivity (μΩ-cm) vs Mothickness (Angstroms), respectively.

Lower resistivity is observed at 60 Torr process pressure than at 45Torr. No significant difference between 500° C. and 520° C. at 60 Torrwas observed. For comparable BW nucleation layer and SW nucleation layerthicknesses, lower resistivity was observed on the SW nucleation layers.Higher resistivity was observed on thinner (fewer cycles) SW nucleationlayers.

Mo was deposited by CVD on WCN at different temperatures (500° C. and520° C.) and pressures (45 Torr and 60 Torr). FIG. 7 shows Mo growthrate and FIG. 8 shows resistivity vs Mo film thickness. FIG. 9 showsthickness and resistivity as a function of WCN underlayer thickness. WCNetching was observed at 45 Torr whereas uniform Mo deposition wasobserved at 60 Torr. At 60 Torr, a higher growth rate at 520° C. wasobserved, with temperature not impacting resistivity. Mo was grown onWCN as thin as 10 Angstroms, with thinner WCN resulting in lowerresistivity. SIMS data showed that CVD Mo on WCN was smooth with lessthan 0.5 (atomic) % total impurities (e.g., O, B, C) in the bulk.

In some embodiments, Mo may be deposited selectively on a metal or pure(no native oxide) Si surface with respect to dielectric underlayers. Forexample, for metal contact or middle of line (MOL) logic applications,Mo can be grown selectively on metal, resulting in bottom-up, void freegap fill. In such applications, the Mo may be deposited directly on ametal or Si surface that is adjacent an exposed silicon dioxide or otherexposed dielectric surface. The nucleation delay on the dielectric issuch that the Mo is deposited preferentially on the metal surface. Forexample, a feature having a metal bottom and silicon dioxide sidewallsmay be exposed to a Mo-containing precursor and a co-reactant. Mo willgrow from the bottom-up rather than from the sidewalls.

Anneal

In some embodiments, a thermal anneal is performed after Mo deposition.This can allow Mo grain growth and lower resistivity. Because themelting point of Mo is lower than that of W, grain growth and theaccompanying decrease in resistivity occur at lower temperatures for Mofilms. Examples of anneal temperatures range from 700° C. to 1100° C.The anneal may be performed in a furnace or by rapid thermal annealing.According to various embodiments, it may be performed in any appropriateambient, including a hydrogen (H₂) ambient, a nitrogen (N₂) ambient, orvacuum.

According to various embodiments, the Mo film may or may not be exposedto air between deposition and annealing. If it is exposed to air orother oxidizing environment, a reducing environment may be employedduring or before anneal to remove molybdenum dioxide (MoO₂) ormolybdenum trioxide (MoO₃) that has formed as a result of the exposure.MoO₃ in particular has a melting point of 795° C. and could melt duringanneal if not removed.

Table 1, below, compares two W films (A and B) and two Mo films (C andD)

A B C D Resistivity 20 μΩ-cm at 28 μΩ-cm at 25 μΩ-cm at 17 μΩ-cm at 20nm 20 nm 10 nm 10 nm 40 μΩ-cm at (after 800 C. 10 nm anneal) Composition<3E18 at/cm³ F <5E18 at/cm³ Cl, 95% Mo + 5% <1% O, <1E19 F belowdetection H, <1E19 at/ at/cm³ Cl limit cm³ Cl Stress <0.55 Gpa @ <0.2Gpa @ 0.4 GPa @ 0.6 GPa @ 30 nm 20 nm 20 nm 70 nm

Film A is a low fluorine tungsten (LFW) film deposited using WF₆. Film Bis a tungsten film deposited using WCl₅ and WCl₆. Film C is a molybdenumfilm deposited using MoCl₅ and film D is a molybdenum film depositedusing MoOCl₄. Film D was subject to a post-deposition anneal. Notably,the resistivity is lower for Films C and D than films A and B.Resistivity decreases with thickness, with the 25μΩ-cm (film C) and17μΩ-cm (film D) directly comparable to the 40μΩ-cm (film A). Film D,deposited with an O-containing precursor, shows low O. The stress offilms C and D is comparable to that of films A and B.

FIG. 10 is a graph showing the reduction in resistivity for Mo films ofvarious thicknesses deposited on WCN after anneal at 800° C. Resistivityof a W film on WCN is also shown for comparison. A significant decreasein resistivity is observed. The decrease in resistivity is due to graingrowth. Table 2, below, shows phases and average grain size for Mograins in as deposited and post-anneal CVD Mo films.

Average Crystallite Sample Phase Size (nm) CVD Mo/WCN Mo - MolybdenumCubic 14.5 as deposited CVD Mo/WCN Mo - Molybdenum Cubic 33.5post-annealFurnace anneals of 1 hour and 5 mins at 800° C. in H₂ ambient showedcomparable results.

Apparatus

Any suitable chamber may be used to implement the disclosed embodiments.Example deposition apparatuses include various systems, e.g., ALTUS® andALTUS® Max, available from Lam Research Corp., of Fremont, Calif., orany of a variety of other commercially available processing systems. Theprocess can be performed on multiple deposition stations in parallel.

In some embodiments, a tungsten nucleation process is performed at afirst station that is one of two, five, or even more deposition stationspositioned within a single deposition chamber. In some embodiments,various steps for the nucleation process are performed at two differentstations of a deposition chamber. For example, the substrate may beexposed to diborane (B₂H₆) in a first station using an individual gassupply system that creates a localized atmosphere at the substratesurface, and then the substrate may be transferred to a second stationto be exposed to a precursor such as tungsten hexachloride (WCl₆) todeposit the nucleation layer. In some embodiments, the substrate maythen be transferred back to the first station for a second exposure ofdiborane or to a third station for a third reactant exposure. Then thesubstrate may be transferred to the second station for exposure to WCl₆(or other tungsten chloride) to complete tungsten nucleation and proceedwith bulk molybdenum deposition in the same or different station. One ormore stations can then be used to perform Mo chemical vapor deposition(CVD) as described above.

FIG. 11 is a block diagram of a processing system suitable forconducting deposition processes in accordance with embodiments describedherein. The system 1100 includes a transfer module 1103. The transfermodule 1103 provides a clean, pressurized environment to minimize therisk of contamination of substrates being processed as they are movedbetween the various reactor modules. Mounted on the transfer module 1103is a multi-station reactor 1109 capable of performing nucleation layerdeposition, which may be referred to as pulsed nucleation layer (PNL)deposition, as well as CVD deposition according to embodiments describedherein. Chamber 1109 may include multiple stations 1111, 1113, 1115, and1117 that may sequentially perform these operations. For example,chamber 1109 could be configured such that stations 1111 and 1113perform PNL deposition, and stations 1113 and 1115 perform CVD. Eachdeposition station may include a heated wafer pedestal and a showerhead,dispersion plate or other gas inlet.

Also mounted on the transfer module 1103 may be one or more single ormulti-station modules 1107 capable of performing plasma or chemical(non-plasma) pre-cleans. The module may also be used for various othertreatments, e.g., reducing agent soaking. The system 1100 also includesone or more (in this case two) wafer source modules 1101 where wafersare stored before and after processing. An atmospheric robot (not shown)in the atmospheric transfer chamber 1119 first removes wafers from thesource modules 1101 to loadlocks 1121. A wafer transfer device(generally a robot arm unit) in the transfer module 1103 moves thewafers from loadlocks 1121 to and among the modules mounted on thetransfer module 1103.

In certain embodiments, a system controller 1129 is employed to controlprocess conditions during deposition. The controller will typicallyinclude one or more memory devices and one or more processors. Theprocessor may include a CPU or computer, analog and/or digitalinput/output connections, stepper motor controller boards, etc.

The controller may control all of the activities of the depositionapparatus. The system controller executes system control softwareincluding sets of instructions for controlling the timing, mixture ofgases, chamber pressure, chamber temperature, wafer temperature, radiofrequency (RF) power levels if used, wafer chuck or pedestal position,and other parameters of a particular process. Other computer programsstored on memory devices associated with the controller may be employedin some embodiments.

Typically there will be a user interface associated with the controller.The user interface may include a display screen, graphical softwaredisplays of the apparatus and/or process conditions, and user inputdevices such as pointing devices, keyboards, touch screens, microphones,etc.

System control logic may be configured in any suitable way. In general,the logic can be designed or configured in hardware and/or software. Theinstructions for controlling the drive circuitry may be hard coded orprovided as software. The instructions may be provided by “programming.”Such programming is understood to include logic of any form, includinghard coded logic in digital signal processors, application-specificintegrated circuits, and other devices which have specific algorithmsimplemented as hardware. Programming is also understood to includesoftware or firmware instructions that may be executed on a generalpurpose processor. System control software may be coded in any suitablecomputer readable programming language. Alternatively, the control logicmay be hard coded in the controller. Applications Specific IntegratedCircuits, Programmable Logic Devices (e.g., field-programmable gatearrays, or FPGAs) and the like may be used for these purposes. In thefollowing discussion, wherever “software” or “code” is used,functionally comparable hard coded logic may be used in its place.

The computer program code for controlling the deposition and otherprocesses in a process sequence can be written in any conventionalcomputer readable programming language: for example, assembly language,C, C++, Pascal, Fortran or others. Compiled object code or script isexecuted by the processor to perform the tasks identified in theprogram.

The controller parameters relate to process conditions such as, forexample, process gas composition and flow rates, temperature, pressure,plasma conditions such as RF power levels and the low frequency RFfrequency, cooling gas pressure, and chamber wall temperature. Theseparameters are provided to the user in the form of a recipe, and may beentered utilizing the user interface.

Signals for monitoring the process may be provided by analog and/ordigital input connections of the system controller. The signals forcontrolling the process are output on the analog and digital outputconnections of the deposition apparatus.

The system software may be designed or configured in many differentways. For example, various chamber component subroutines or controlobjects may be written to control operation of the chamber componentsnecessary to carry out the inventive deposition processes. Examples ofprograms or sections of programs for this purpose include substratepositioning code, process gas control code, pressure control code,heater control code, and plasma control code.

In some implementations, a controller 1129 is part of a system, whichmay be part of the above-described examples. Such systems can includesemiconductor processing equipment, including a processing tool ortools, chamber or chambers, a platform or platforms for processing,and/or specific processing components (a wafer pedestal, a gas flowsystem, etc.). These systems may be integrated with electronics forcontrolling their operation before, during, and after processing of asemiconductor wafer or substrate. The electronics may be referred to asthe “controller,” which may control various components or subparts ofthe system or systems. The controller 1129, depending on the processingrequirements and/or the type of system, may be programmed to control anyof the processes disclosed herein, including the delivery of processinggases, temperature settings (e.g., heating and/or cooling), pressuresettings, vacuum settings, power settings, radio frequency (RF)generator settings in some systems, RF matching circuit settings,frequency settings, flow rate settings, fluid delivery settings,positional and operation settings, wafer transfers into and out of atool and other transfer tools and/or load locks connected to orinterfaced with a specific system.

Broadly speaking, the controller may be defined as electronics havingvarious integrated circuits, logic, memory, and/or software that receiveinstructions, issue instructions, control operation, enable cleaningoperations, enable endpoint measurements, and the like. The integratedcircuits may include chips in the form of firmware that store programinstructions, digital signal processors (DSPs), chips defined asapplication specific integrated circuits (ASICs), and/or one or moremicroprocessors, or microcontrollers that execute program instructions(e.g., software). Program instructions may be instructions communicatedto the controller in the form of various individual settings (or programfiles), defining operational parameters for carrying out a particularprocess on or for a semiconductor wafer or to a system. The operationalparameters may, in some embodiments, be part of a recipe defined byprocess engineers to accomplish one or more processing steps during thefabrication of one or more layers, materials, metals, oxides, silicon,silicon dioxide, surfaces, circuits, and/or dies of a wafer.

The controller 1129, in some implementations, may be a part of orcoupled to a computer that is integrated with, coupled to the system,otherwise networked to the system, or a combination thereof. Forexample, the controller 1129 may be in the “cloud” or all or a part of afab host computer system, which can allow for remote access of the waferprocessing. The computer may enable remote access to the system tomonitor current progress of fabrication operations, examine a history ofpast fabrication operations, examine trends or performance metrics froma plurality of fabrication operations, to change parameters of currentprocessing, to set processing steps to follow a current processing, orto start a new process. In some examples, a remote computer (e.g. aserver) can provide process recipes to a system over a network, whichmay include a local network or the Internet. The remote computer mayinclude a user interface that enables entry or programming of parametersand/or settings, which are then communicated to the system from theremote computer. In some examples, the controller receives instructionsin the form of data, which specify parameters for each of the processingsteps to be performed during one or more operations. It should beunderstood that the parameters may be specific to the type of process tobe performed and the type of tool that the controller is configured tointerface with or control. Thus as described above, the controller maybe distributed, such as by including one or more discrete controllersthat are networked together and working towards a common purpose, suchas the processes and controls described herein. An example of adistributed controller for such purposes would be one or more integratedcircuits on a chamber in communication with one or more integratedcircuits located remotely (such as at the platform level or as part of aremote computer) that combine to control a process on the chamber.

Without limitation, example systems may include a plasma etch chamber ormodule, a deposition chamber or module, a spin-rinse chamber or module,a metal plating chamber or module, a clean chamber or module, a beveledge etch chamber or module, a physical vapor deposition (PVD) chamberor module, a CVD chamber or module, an ALD chamber or module, an atomiclayer etch (ALE) chamber or module, an ion implantation chamber ormodule, a track chamber or module, and any other semiconductorprocessing systems that may be associated or used in the fabricationand/or manufacturing of semiconductor wafers.

As noted above, depending on the process step or steps to be performedby the tool, the controller might communicate with one or more of othertool circuits or modules, other tool components, cluster tools, othertool interfaces, adjacent tools, neighboring tools, tools locatedthroughout a factory, a main computer, another controller, or tools usedin material transport that bring containers of wafers to and from toollocations and/or load ports in a semiconductor manufacturing factory.

The controller 1129 may include various programs. A substratepositioning program may include program code for controlling chambercomponents that are used to load the substrate onto a pedestal or chuckand to control the spacing between the substrate and other parts of thechamber such as a gas inlet and/or target. A process gas control programmay include code for controlling gas composition and flow rates andoptionally for flowing gas into the chamber prior to deposition in orderto stabilize the pressure in the chamber. A pressure control program mayinclude code for controlling the pressure in the chamber by regulating,e.g., a throttle valve in the exhaust system of the chamber. A heatercontrol program may include code for controlling the current to aheating unit that is used to heat the substrate. Alternatively, theheater control program may control delivery of a heat transfer gas suchas helium to the wafer chuck.

Examples of chamber sensors that may be monitored during depositioninclude mass flow controllers, pressure sensors such as manometers, andthermocouples located in pedestal or chuck. Appropriately programmedfeedback and control algorithms may be used with data from these sensorsto maintain desired process conditions.

The foregoing describes implementation of embodiments of the disclosurein a single or multi-chamber semiconductor processing tool.

The foregoing describes implementation of disclosed embodiments in asingle or multi-chamber semiconductor processing tool. The apparatus andprocess described herein may be used in conjunction with lithographicpatterning tools or processes, for example, for the fabrication ormanufacture of semiconductor devices, displays, LEDs, photovoltaicpanels, and the like. Typically, though not necessarily, suchtools/processes will be used or conducted together in a commonfabrication facility. Lithographic patterning of a film typicallycomprises some or all of the following steps, each step provided with anumber of possible tools: (1) application of photoresist on a workpiece,i.e., substrate, using a spin-on or spray-on tool; (2) curing ofphotoresist using a hot plate or furnace or UV curing tool; (3) exposingthe photoresist to visible or UV or x-ray light with a tool such as awafer stepper; (4) developing the resist so as to selectively removeresist and thereby pattern it using a tool such as a wet bench; (5)transferring the resist pattern into an underlying film or workpiece byusing a dry or plasma-assisted etching tool; and (6) removing the resistusing a tool such as an RF or microwave plasma resist stripper.

CONCLUSION

Although the foregoing embodiments have been described in some detailfor purposes of clarity of understanding, it will be apparent thatcertain changes and modifications may be practiced within the scope ofthe appended claims. It should be noted that there are many alternativeways of implementing the processes, systems, and apparatus of thepresent embodiments. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the embodiments arenot to be limited to the details given herein.

1.-17. (canceled)
 18. A method comprising: providing a substratecomprising a feature having a dielectric surface; forming a molybdenumlayer directly on the dielectric surface without an interveningdiffusion barrier layer.
 19. The method of claim 18, wherein forming themolybdenum layer comprises forming a reducing agent layer on thedielectric surface.
 20. The method of claim 19, wherein forming themolybdenum layer further comprises exposing the reducing agent layer toa molybdenum-containing precursor.
 21. The method of claim 20, whereinthe reducing agent layer is converted to molybdenum by the exposure. 22.The method of claim 19, wherein the reducing agent layer is conformal tothe feature.
 23. The method of claim 2, wherein the reducing agent layeris between 10 Angstroms and 50 Angstroms thick.
 24. The method of claim18, wherein the dielectric surface is a silicon oxide surface.
 25. Themethod of claim 18, wherein the dielectric surface is a silicon nitridesurface
 26. The method of claim 18, wherein the dielectric surface is analuminum oxide surface.
 27. The method of claim 18, wherein the featurefurther comprises a conductive surface.
 28. The method of claim 18,wherein molybdenum layer has less than 1 (atomic) % impurities.
 29. Themethod of claim 18, wherein molybdenum layer is formed from one of:molybdenum hexafluoride (MoF₆), molybdenum pentachloride (MoCl₅),molybdenum dichloride dioxide (MoO₂Cl₂), molybdenum tetrachloride oxide(MoOCl₄), and molybdenum hexacarbonyl (Mo(CO)₆).
 30. The method of claim18, wherein molybdenum layer is formed from an organometallic precursor.31. A method comprising: providing a substrate comprising a featurehaving a dielectric surface; forming a conformal reducing agent layer inthe feature including directly on the dielectric surface; and exposingthe reducing agent layer to a molybdenum-containing precursor to form aconformal molybdenum layer including directly on the dielectric surface.32. The method of claim 31, wherein the reducing agent layer is between10 Angstroms and 50 Angstroms thick.
 33. The method of claim 31, whereinthe dielectric surface is a silicon oxide surface, a silicon nitridesurface, or an aluminum oxide surface.
 34. The method of claim 31,wherein the molybdenum precursor is one of molybdenum hexafluoride(MoF₆), molybdenum pentachloride (MoCl₅), molybdenum dichloride dioxide(MoO₂Cl₂), molybdenum tetrachloride oxide (MoOCl₄), and molybdenumhexacarbonyl (Mo(CO)₆).
 35. The method of claim 31, wherein molybdenumprecursor is an organometallic precursor.
 36. A method comprising:depositing a molybdenum-containing nucleation layer on a substrate usinga first reducing agent; and depositing by chemical vapor deposition(CVD) a molybdenum bulk layer on the molybdenum nucleation layer using asecond reducing agent, wherein the second reducing agent is differentfrom the first reducing agent.
 37. The method of claim 36, wherein themolybdenum bulk layer is deposited by a reducing a molybdenum compoundselected from: molybdenum hexafluoride (MoF₆), molybdenum pentachloride(MoCl₅), molybdenum dichloride dioxide (MoO₂Cl₂), molybdenumtetrachloride oxide (MoOCl₄), and molybdenum hexacarbonyl (Mo(CO)₆).